The present invention relates to a method for the abrading machining of a workpiece with random convex and/or concave, planar or curved surfaces, by means of at least one end-face cutting tool, the orientation of which relative to the surface of the workpiece is set in such a way that the contact line or curve or the contact point between the tool and the workpiece surface is located on the end face of the tool, as well as to a tool for performing this method.
Of the various known methods for the machining of the surfaces of a workpiece, without doubt, turning or rotary milling is one of the most suitable machining methods for producing a cylindrical or disk-like workpiece with excellent surface characteristics. Surfaces produced by such method are equivalent as regards quality to ground and polished workpiece surfaces and can even satisfy optical requirements. Examples of such surfaces are metal mirrors, printing rollers and similar workpieces.
If it is desired to obtain very fine surfaces by milling cutting, appropriately consideration is given to the rotary or turning milling method. However, the restriction exists in the application of such method to workpieces in which it is possible to work cylindrical shapes having throughout a convex cross-section up to a maximum of planar contours using the planar end face of a milling tool. This method does not make it possible to machine concave surfaces on workpieces. Thus, the known method is restricted to cylindrical to slightly domed workpieces with a convex cross-section. If it is necessary to machine randomly curved surfaces on workpieces, particularly those having concave portions, it is necessary to choose a different machining method.
A milling method frequently used in such cases, in which a shank-type milling cutter referred to as a ball-end cutter, having a spherical end and using three translatory movement axes at right angles to one another, is guided on planar or spatially curved paths over the workpiece, leads to a relatively rough surface at right angles to the feed direction and also in the feed direction. However, accessibility is very good, i.e. there are few collision problems, which normally reside in reciprocally disturbing or interfering positions between the milling cutter with its spindle and the workpiece with any random holding device.
Another milling method for machining random surfaces of workpieces is the method referred to as collapse or collision milling, which is carried out using five movement axes. As a result of the closer adaptation of the milling cutter edge to the surface of the workpiece in this method, the side roughness is significantly reduced, but a considerable roughness occurs in the feed direction due to the traces of the individual cutter teeth. Generally, accessibility is adequate, because the collision problems are only solved to an insignificantly inferior extent than in the case of triaxial methods with ball-end milling cutters.
Another known machining method for random surfaces of workpieces is the circumferential and flank milling, which is performed with cylindrical or disk-shaped milling cutters. In the case of circumferential milling with a cylindrical milling cutter the feed takes place in a direction substantially at right angles to the milling cutter axis. As a function of the cutter construction a very good roughness can be obtained in the feed direction and also at right angles thereto.
However, due to the fact that the cutter axis must be parallel or almost parallel to the workpiece surface, the accessibility is greatly restricted due to the collision problems which occur. The use of such method is consequently limited to a few applications, e.g. to the machining of turbine blades.